Hand use predicts the structure of representations in sensorimotor cortex.

Area of Science:

• Neuroscience
• Motor Control
• Neuroimaging

Background:

• The primary motor cortex controls fine finger movements via neural population activity.
• Previous research suggests this area represents multi-joint movements, but organizational principles remain unclear.

Purpose of the Study:

• To investigate the organizational principles of finger representations in the primary motor cortex.
• To determine how hand use influences neural activity patterns related to finger movements.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to analyze neural activity patterns during individuated finger movements.
• Activity patterns were analyzed for their spatial layout and relative similarity.
• The correlation structure of everyday hand movements and muscle activity were used for comparison.

Main Results:

• Finger-specific activity patterns in the motor cortex showed variable spatial layouts but preserved relative similarity across participants.
• The organization of these patterns was better explained by the correlation structure of everyday hand movements than by muscle activity.
• This organizational structure correlated with involuntary finger co-contraction patterns during high-force tasks.

Conclusions:

• The relative arrangement of finger-specific activity patterns in sensory-motor cortex is shaped by hand use.
• Neural representations in the motor cortex adapt to the functional demands of hand movements.